This invention relates to an apparatus for removing liquids from various moist or mucky solid or semi-solid materials such as sewerage sludge, industrial waste, agricultural waste, animal waste, waste from food processes, and the like. More particularly, the invention is directed to a continuous drying apparatus which utilizes conveyor belts to move moist material which is to be dried through a plurality of vertically stacked heating chambers, through which hot gases are passed in a generally upwardly direction to the material which is to be dried, and which include a plurality of radiative-type heating devices.
Various drying apparatuses have been employed to remove liquids, especially water, from a variety of waste product streams in order to lower the moisture content of the waste to reduce costs associated with transporting the waste to a landfill. Additionally, drying or dewatering of such wastes is frequently required before the landfill operator can allow disposal of the waste at the landfill site. Known continuous apparatus have generally been designed with a relatively narrow width and height and a relatively long linear flow path. As a result, known continuous drying apparatuses have a relatively high ratio of external surface area to drying volume which leads to heat losses through the top, floor, and sidewalls of the dryer which can be higher than might be desirable. Also, the linear flow path of most drying apparatuses often requires more floor space than might be desirable.
Another disadvantage of known drying apparatuses is that they are generally designed so that the moist solid or semi-solid material which is to be dried travels through the dryer unit at a constant velocity, even though the material continuously loses mass and volume due to the evolution of moisture as it travels through the dryer unit. This results in inefficient utilization of the drying and mass handling capacity of the apparatus.
Accordingly, it is an objective of the invention to provide a drying apparatus which is more compact, achieves lower heat losses through the walls, floor, and top of the dryer unit, and which can more efficiently utilize the heating and mass handling capacity of the dryer unit.